The present invention relates to a vehicle body structure of a rear part of a vehicle.
A vehicle body structure of a rear part of a vehicle is formed into a ladder configuration in which left and right side members are extended in a front-to-rear direction of a vehicle body and cross members are then extended between the side members. A kick-up floor portion which is raised in height in a step-like fashion is formed at a rear side of a vehicle body frame. Additionally, the side members are also formed so as to be raised in height in a step-like fashion to follow the kick-up floor portion.
Incidentally, on many occasions, a rear seat is disposed at the kick-up floor portion at the rear part of the vehicle for provision of a seating space for passengers. It is also currently adopted practice to dispose a fuel tank underneath the kick-up floor portion on many occasions. Due to this configuration, the kick-up floor portion needs to be restricted from being deformed to secure the passenger space and protect the fuel tank when the vehicle is involved in a rear collision. It is considered that the side members are reinforced to restrict the deformation of the kick-up floor portion.
Although it is considered that the rigidity of material of the side members is enhanced or reinforcement members are added to reinforce the side members, this will call for an increase in weight of the vehicle. In addition, since the side members are raised in height at the kick-up floor portion, loadings from the rear part produce a bending moment at step portions of the side members, and therefore, the amount of reinforcement at the step portions needs to be increased, and this leads to a problem that a further increase in weight will be called for.
Then, in order to reduce loadings applied to the vehicle when the vehicle is involved in a rear collision, the structure has conventionally been proposed in which a skeletal member extending to the front of a vehicle is disposed at a central portion of the vehicle and side members and the skeletal member are connected together by a frame, so that loadings applied to the side members from the rear are dispersed to the skeletal member (refer to Patent Literature 1). In the structure disclosed in Patent Literature 1, the impact loadings applied from the rear can be dispersed to the whole of the vehicle.
In the technique disclosed in Patent Literature 1, however, since part of the loadings applied to the side members from the rear is received by the frame and the rigidity of the skeletal member, the loading bearing reduction effect is limited, in reality, the loading bearing reduction effect does not match the increase in weight as a result of the addition of the frame and the skeletal member.
[Patent Literature 1] Japanese Patent No. 4571340